Speaking to the BBC, Joyce said Qantas hoped to place an order next year, which could see the non-stop route launch in 2022 - if the aircraft manufacturers are up to the task.
The approximately 20-hour flight would eclipse Qantas’s 17-hour non-stop London-Perth service, launched earlier this year.
The London-Perth service is currently operated by Boeing 787 Dreamliner aircraft but Qantas believe the additional duration and burden of a London-Sydney route would require a different aircraft.
Joyce told BBC Radio 4’s Today Programme there would be demand from both the business and leisure sector, adding not having to stop and change was a vital selling point for such an endeavour.
Codenamed Project Sunrise, Joyce said while Qantas had looked at Airbus’s A350-1000 for the route, it would require modification to increase its range. Another option is Boeing’s 777-8, which is due to enter service in 2022.
Joyce added if a suitable aircraft could be found, Qantas would likely look at non-stop New York flights too.
Qantas’s London-Perth route, at 9,009 miles, is currently the world’s second longest flight in terms of distance, Qatar Airways’ Doha-Auckland service 23 miles further.
These though look set to be beaten comprehensively by Singapore Airlines direct Singapore-New York service, some 500 miles further.